Problem: Evaluate the following expression when $x = 10$ and $y = 8$. $7$ $x$ $ + 6$ $y$ $ - 7$
Answer: Substitute $10$ for ${x}$ and $8$ for ${y}$ $ = 7{(10)} + 6{(8)} - 7 $ $ = 70 + 48 - 7 $ $ = 111$